Method of producing slips for oil well tools



April 4, 1939. c, E, BURT METHQD OF PRODUCING SLIPS FOR OIL WELL TOOLS 2 Sheets-Sheet 1 mlilg.

Filed Jan. 21, 1957.

INVENTOR.

ATTORNEY ?aftenteoi Apr. 4%,, 11939 UNITED STATES PATENT OFFICE Clarence E. Burt, Los Angeles, Calif., assignor to lBaker Oil Tools, Inc., Huntington Park, Calif., a corporation of California Application January 21, 1937, Serial No. 121,539

1 Claim.

This invention relates to a method of producing slips for use in connection with oil well tools.

It is the principal object of my present invention to provide an improved method of producing slips for use on cement retainers, fishing tools and the like employed in oil well bores, by which method improved slips are produced in a very economical fashion.

The invention is exemplified in the following description and illustrated by way of example in the accompanying drawings, in which:

Fig. 1 is a perspective view showing slips produced in accordance with my method on an expanding cone in an oil well casing prior, to being placed into engagement with the casing.

Fig. 2 shows the slips expanded'into gripping position relative to the casing.

Fig. 3 is a plan view of the structure illus trated in Fig. 1, the well casing being shown in section.

Fig. 4 is a perspective view of the slip casting showing the manner in which it is divided to form segments.

5 is a sectional view taken on line V-V of Fig. 6 is a transverse sectional view taken on line VI-VI of Fig. 9. a

Fig. 7 is a. transverse sectional view taken on line VII-V1I of Fig. 10.

Figs. 8, 9 and 10 are fragmentary views in vertical section through a well casing showing a slip and a slip cone positioned therein, the three views showing the slip in three different positions relative to the casing.

Referring more particularly to the accompanying drawings, It indicates a slip casting which is cast in the form of a ring and which is ultimately divided to form three segmental slips H. The inner periphery of the casting is formed with a conical bore M to coincide with a slip expanding cone IS on the oil tool to which the slips are to be applied. In the present instance I have shown the slips i2 as connected to the cone i5 by.

means of shear pins l6.

As before stated, the .slip casting i0 is in the form of a cylindrical ring, as illustrated, having wickers ll circumscribing its exterior periphery. In casting, a chill is provided for the exterior surface so that the wickers will be hardened to provide a proper cutting edge. The hard,

purpose that will be later herein described.

During the casting of the slip casting, three longitudinally extending radial slots I! are cast in the inner periphery of the casting and extend from its upper to its lower end. Also, during the casting, three longitudinally extending semicircular weakening grooves B8 are formed in the slip casting intermediate the slots ll. These grooves form weakened points in the ring casting and extend longitudinally thereof for the After the casting has been produced, the conical bore i4 thereof is ground so as to make a proper fit with the cone i5. Thereafter the wickers are ground as disclosed in my copending application above referred to. During this process the exterior of the ring may be trued by grinding in the event the casting is nottruly circular, so that the exterior thereof will be substantially concentric with the bore l4. Thereafter a wedge or other means is inserted in the slots H and m given a sharp blow which causes the casting to fracture along the line of the slots l! as illustrated in Fig. 4 to divide the casting into three segmental slips. The rough edges are then ground and the slips are applied by the shear pins i6 3,5 to the cone l5.

When the slips are expanded by moving relative to the cone, the conical surface of the slips will not truly coincide with the larger diameter of the cone so that they will engage the same at 80 their opposite side edges as illustrated in Fig. 6. Likewise, the radius of the exterior of the slips will be less than the interior diameter of the well casing. Therefore, to provide a perfect gripping action between the slips and the cone, when 86 pressure is-applied to cause the. wickers of the slips to grip the casing, they will fracture vettically along their weakened center portions, weakened asbefore mentioned by providing the grooves It. This will double the number of slips (0 and likewise cause them to conform as closely as possible with the interior bore of the well casing so as to provide a good gripping action. By doubling the number of the slips due to the fracturing as before stated, the slips are more likely to Y be moreevenly distributed about the casing in the event that they shift circumferentially during expansion.

From the foregoing it is seen that by my method of producing slips, I can cast them in a single ring so that they may be all ground'and fitted to the cone together and trued up, and that they may thereafter be'easily and quickly sepa-. rated for application to the cone.

It is also obvious that by providing the weak-, as

ened grooves I8, that a better gripping action will be provided between the casing and the slips as before stated.

While .I have disclosed my invention in detail, it is to be understood that various changes may be made in its construction by those skilled in the art without departing from the spirit of the invention as defined in the appended claim.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

A method of producing cast iron slips which comprises producing a slip casting in the form of a ring, forming longitudinal slots in the inner wall of said casting at spaced circumferential points thereabout during the casting thereof, forming weakening grooves longitudinally in the casting during the casting thereof and intermediate said slots, forming hard sharp wickers circumscribing the exterior surface of said casting,

grinding the interior bore of said casting, truing the exterior of said casting to conform with said bore, and then fracturing said casting at each of said slots to form segmental slips. said weakening grooves enabling said slips to fracture vertically when they are placed in gripping position relative to a casing.

CLARENCE E. BURT. 

